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  • 1
    Electronic Resource
    Electronic Resource
    Microscopic characterization of low-field switching in ferroelectric triglycine sulfate (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 84 (1998), S. 3802-3805 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Low-field (〈1 kV/cm) switching has been investigated for thin plates (0.06〈d〈0.15 cm) of triglycine sulfate by means of field pulses with a linear rise time. The dependence of the maximum current density, jm, with the field value Em at which this maximum occurs is jm≅B1(Em−Ecw1)3/2, for 0.3〈Em〈0.5 kV/cm, and jm≅B2(Em−Ecw2), for 0.5〈Em〈1.0 kV/cm. This is satisfactorily explained taking into account the dominant role played by sidewise and forward domain wall motion, respectively. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.368590
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  • 2
    Electronic Resource
    Electronic Resource
    Evaluation of on-line coupling size exclusion chromatography electrothermal atomic absorption spectrometry for selenium speciation (1997)
    Springer
    Fresenius' journal of analytical chemistry 357 (1997), S. 837-843 
    Details
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract  Chromatographic effluents were on-line analyzed by Zeeman-ETAAS, using a flow-through cell placed in a graphite furnace autosampler as interface. To obtain high sampling rates, the use of fast graphite furnace programmes was studied. Conventional programmes of 96 s were reduced to 18 s by using hot injection (120 °C) and reducing the charring step to 2 s. The increase of the injection volume from 20 to 60 μl lengthened the programme to 46 s. Nickel had to be added to get a comparable response for both inorganic and organic selenium species (selenite and selenomethionine) and to reduce the interferent effect produced in presence of the chromatographic eluent (TRIS 0.01 mol l-1, NH4NO3 0.1 mol l-1, pH 7). The optimized conditions were applied to the speciation of selenium in human erythrocyte lysates by size exclusion LC-ETAAS. Using a high performance size exclusion column selenium could be assigned to proteins of 100 and 35 kDa. Detection limits in the range of 1 ng (2 μg l-1 for 500 μl injection volume) were obtained for the combined technique.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002160050259
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  • 3
    Electronic Resource
    Electronic Resource
    Classification of ancient Roman glazed ceramics using the neural network of Self-Organizing Maps (2000)
    Springer
    Fresenius' journal of analytical chemistry 367 (2000), S. 586-589 
    Details
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Artificial neural networks with unsupervised learning strategy known as Self-Organizing Maps were applied to classify ancient Roman glazed ceramics. Their clay ceramic bodies were analyzed by Inductively Coupled Plasma-Atomic Emission Spectroscopy and the chemical composition obtained was processed by this neural algorithm. The results obtained provide two types of information: firstly, classification of ceramic samples with identification of several groups and secondly, differentiation between the elemental chemical information. It was found that there are certain chemical elements which can be considered as principal and which can serve to differentiate between ceramics, whereas other elements give redundant information and do not contribute to sample differentiation. Seven chemical elements were considered principal and provide the necessary information. Two types of element were identified: 1 – a group formed by common elements, such as: Ca, Fe, Mg, Mn and 2 – another formed by optional elements: K or Na and Ba or Sr and Al or Ti.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002160000433
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  • 4
    Electronic Resource
    Electronic Resource
    Determination of direct-bilirubin by a fluorimetric-enzymatic method based on bilirubin oxidase (2000)
    Springer
    Fresenius' journal of analytical chemistry 368 (2000), S. 516-521 
    Details
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A method for the determination of direct bilirubin by reaction with bilirubin oxidase (BOx) is reported. The procedure is based on the changes in fluorescence which take place during the enzymatic reaction of BOx with any of the three forms of bilirubin (free, conjugated and with albumin) when the solution is excited at 240 nm and the emission is measured at 440 nm. The change in fluorescence was studied thoroughly. It seems mainly due to the fluorescence of one of the reaction products. A theoretical study was carried out to relate the changes in fluorescence observed to the species taking part in the reaction and to establish some of the enzymatic reaction constants. The optimum reaction conditions were studied for each of the three types of bilirubin together with their analytical characteristics (linear range and precision). Selective determination of direct bilirubin was carried out for various synthetic samples with good results. A linear response up to 7 mg L–1 of direct bilirubin was obtained. Using optimum conditions, the precision for free and conjugated bilirubin was 3.4% (n = 5) and 3.0% (n = 5), respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002160000503
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  • 5
    Electronic Resource
    Electronic Resource
    Liver injury caused by ebrotidine: a new example of the utility of the postmarketing surveillance (2000)
    Springer
    European journal of clinical pharmacology 56 (2000), S. 187-189 
    Details
    ISSN: 1432-1041
    Keywords: Key words Ebrotidine ; Liver injury ; Post-marketing surveillance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002280050739
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  • 6
    Electronic Resource
    Electronic Resource
    Speciation of antimony by differential generation of its volatile covalent hydride in aqueous and organic phase (1986)
    Springer
    Microchimica acta 90 (1986), S. 95-103 
    Details
    ISSN: 1436-5073
    Keywords: antimony ; speciation ; hydride generation ; AAS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract By using the ammonium pyrrolidinedithiocarbamate (APDC) — methylisobutyl ketone (MIBK) extraction system Sb(III) is extracted into the organic phase. Sb(III) is directly determined in this organic phase by hydride generation AAS using NaBH4/dimethylformamide solution as reducing agent. Sb(V) is determined in the aqueous phase using the same technique.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01196824
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  • 7
    Electronic Resource
    Electronic Resource
    Volatile phase introduction of metallic beta-diketonates in atomic absorption spectrometry: Zinc acetylacetonate (1986)
    Springer
    Microchimica acta 90 (1986), S. 407-416 
    Details
    ISSN: 1436-5073
    Keywords: atomic absorption spectrometry ; volatile phase ; zinc determination ; beta-diketonates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The combined method volatile phase-atomic spectroscopy is an improvement in comparison with the conventional method of liquid sample introduction. The generation of a volatile phase by sublimation from an ethanolic solution of zinc acetylacetonate monohydrate and the obtainment of an analytical signal by AAS is proposed in this paper. The volatile phase is introduced in a silica tube by means of a nitrogen stream as carrier gas. The proposed method gives an improved sensitivity of 6.2 times with respect to the introduction of the same sample in liquid phase and more than 30 times with respect to the introduction of the zinc as chloride in aqueous solution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01199281
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  • 8
    Electronic Resource
    Electronic Resource
    Electrocatalytic behaviour of several cobalt complexes: Determination of hydrazine at neutral pH (1997)
    Springer
    Journal of applied electrochemistry 28 (1997), S. 65-70 
    Details
    ISSN: 1572-8838
    Keywords: carbon paste electrode ; mediator ; electrocatalysis ; hydrazine ; cobalt complexes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Four cobalt complexes (cobalt(II) acetylacetonate and 8-hydroxyquinolinate and cobalt(III) 8-hydroxyquinolinate and diethyldithiocarbamate) were tested as mediators to modify carbon paste electrodes with a view to obtaining a catalytic effect for the hydrazine. Cobalt(II) acetylacetonate was found to exert no catalytic effect as the likely result of ligand having to stabilize higher oxidation states of Co potentially involved in the catalytic process. The effects of the electrolyte and pH were examined and found to be important. The proposed chronoamperometric determination for hydrazine features limits of detection at the 99% confidence level of 1.6mM with cobalt(III) diethyldithiocarbamate, 1.5mM with cobalt(III) 8-hydroxyquinolinate and 2.0mM with Co(II) 8-hydroxyquinolinate. The RSD for 2mM hydrazine was always less than 8%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003249802216
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  • 9
    Electronic Resource
    Electronic Resource
    Flame Atomic Absorption Spectrometric Determination of Arsenic After Volatilization of As(III) with Chloride Ions (1999)
    Springer
    Microchimica acta 131 (1999), S. 225-230 
    Details
    ISSN: 1436-5073
    Keywords: Keywords. Arsenic determination; flame atomic absorption; chloride volatilization; insectide sample.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract.  The generation of volatile species of As(III) as a means to introduce arsenic into a flame atomic absorption spectrometer has been studied. The method is based on the reaction between As(III) and chloride ions in sulphuric acid medium. The reaction is performed in a discontinuous or batch mode. With this method 130 μl of a solution containing 17.5% (w/v) sodium chloride and As(III) are injected by a 500 ml.min−1 N2 carrier gas flow into 1 ml of concentrated sulphuric acid. The gaseous compounds generated are introduced into the spectrometer through the nebulizer and As is determined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00013459
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  • 10
    Electronic Resource
    Electronic Resource
    Influence of oxidising agents in lead determination by hydride generation direct flame atomic absorption spectroscopy (1985)
    Springer
    Microchimica acta 85 (1985), S. 253-263 
    Details
    ISSN: 1436-5073
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Es wird über den Einfluß der Oxidantien Cr2O7, MnO4 −, Ce4+, H2O2 und S2O8 2 − auf die Bleibestimmung als kovalentes Hydrid berichtet. Für jede oxidierende Substanz werden die Reaktionsbedingungen optimiert (pH, Menge und Konzentration des Oxidans, Menge und Konzentration von NaBH4 und Reaktionszeit), um Empfindlichkeit und Nachweisgrenze durch Peakhöhenauswertung zu bestimmen. Die Wiederfindungsrate wurde durch elektrothermale Atomabsorptionsspektrometrie von Blei in der Lösung bestimmt. Der Zusammenhang zwischen dem Logarithmus der Extinktion und dem Redoxpotential des Oxidans ergibt eine lineare Beziehung mit einem Korrelationskoeffizienten von 0.999. Die Ergebnisse und deren Interpretation werden in dieser Arbeit beschrieben.
    Notes: Summary The influence of Cr2O7 2−, MnO4 −, Ce4+, H2O2 and S2O8 2− as oxidising agents in lead determination as volatile covalent hydride using NaBH4 is reported in this paper. The reaction conditions for every oxidising agents (pH, quantity and concentration of the oxidising agent, quantity and concentration of the NaBH4 and reaction time) are optimized, determining sensitivity and detection limit by measuring the peak height. The recovery of lead from solution has been measured by flameless atomic absorption spectroscopy. A linear relationship the logarithm of absorbance values and the redox potential of the system is obtained with a correlation coefficient of 0.999. The results and their interpretation are given in this paper.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01198298
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